If Jews are not allowed to eat pork why in the Bible appear pig farmers?

A question that isn't really that important, however, it comes to my mind every time I read some Scripture verses. If the Mosaic Law forbids the consumption of pork meat, why do we see a pig farmer mentioned in the parable of the prodigal son, and some demons begging Jesus to send them in pigs (and it is mentioned that a swineherd man is taking care of them)? I know that Jesus states that nothing from outside (food) is unclean, or that no food is unclean unless you think is unclean, however, He told these parables to Jews so it means it was a common practice to keep pigs as livestock, and the swineherd that was taking care of the pigs, didn't know that Jesus announced that no food is forbidden. So the question is why did Jews at that time raise pigs if they don't eat pork, and pigs don't really have any other utility than consuming (maybe pork skin was used for shoes, however, this doesn't make it worth raising a pig to take its skin and to throw the meat away).